The invention relates to lightweight automatic portable firearms of the type generally known as submachine guns.
An automatic firearm fires continuously so long as the trigger of the weapon is depressed. Rounds of ammunition are automatically loaded into position to be fired, the rounds fired, and the fired cases ejected repeatedly at rapid rates. In a typical submachine gun these steps may be repeated so as to fire from 500 to 800 rounds per minute. If, as is common, the weapon takes a 9 mm parabellum cartridge, each round will produce 33-35,000 psi pressure within the weapon upon detonation. To be acceptable, a weapon design must be capable of repeating the above firing sequence reliably and safely at these high rates under the extremes of pressure and temperature.
Moreover, conditions of use in the field put further limitations on acceptable weapon designs. The weapon may be subjected to rough handling and inhospitable environmental conditions. The weapon must be designed so as to minimize the possibility of jamming or other malfunctions. And it should preferably be constructed so that it may be easily disassembled for cleaning and repairs in the field.